The Arcuate Eminence and Superior Semicircular Canal: Magnetic Resonance Imaging Study.

Objective: The present study aimed to explore the relationship between the arcuate eminence (AE) and superior semicircular canal (SSC) using the constructive interference steady-state (CISS) sequence.

Patients And Methods: After conventional magnetic resonance imaging, a total of 71 patients underwent the CISS sequence in thin-sliced coronal sections.

Results: In all patients, the SSC was delineated on both sides. In contrast, the AE was identified only in 29 of 71 patients (40.8%) on both sides, varying in shape and relative location to the SSC in the mediolateral dimension. The shortest distance between the highest point of the SSC and middle fossa floor was 1.3 ± 1.1 mm on the right side and 1.3 ± 0.9 mm on the left with considerable variability. A dehiscent SSC with a distance less than 0.2 mm was found in 11.3% of 142 sides. On 22 sides (15.5%), the site on the middle fossa floor, reaching the SSC with the shortest distance (reference point) corresponded to the apex of the AE, equally on the right and left. On 36 sides (25.4%), the distance between the reference point and the apex of the AE was measured as 3.0 ± 1.1 mm on the 18 right sides and 3.7 ± 1.6 mm on the 18 left sides.

Conclusions: The relationship between AE and SSC is highly variable. Arcuate eminence was not a reliable landmark of the SSC. High-resolution CISS sequence is useful for exploring these structures.